Subbing layers



United States Patent 3,495,985 SUBBING LAYERS Lodewijk Felix De Keyser, Mortsel-Antwerp, Andre Jan Conix, Antwerp, and Joseph Antoine Herbots, Edegem, Belgium, assignors to Gevaert Photo-Producten N.V., Mortsel, Belgium, a company of Belgium No Drawing. Continuation of application Ser. No.

572,217, Aug. 15, 1966, which is a continuation-inpart of application Ser. No. 201,281, June 11, 1963. This application Nov. 25, 1968, Ser. No. 778,862 Claims priority, application Belgium, June 12, 1961,

' 40,724, Patent 604,869

Int. Cl. G03c 1/ 78 US. Cl. 96-87 12 Claims ABSTRACT OF THE DISCLOSURE A multilayer photographic film including a biaxially stretched polyester film support, a light-sensitive silver halide emulsion layer undersubbed by a mixed gelatincellulose nitrate layer, and a subbing layer intervening between the polyester film support and the undersubbing layer, consisting essentially of -a polyester soluble in chlorinated aliphatic hydrocarbons and prepared by the condensation of at least one aliphatic diol with a diacid component essentially consisting of about 55 to 100 mol percent of isophthalic acid, about 0 to 25 mol percent of terephthalic acid, and about 0 to 20 mol percent of aliphatic saturated dicarboxylic acid.

This invention relates to photographic film elements, more particularly to photographic film elements comprising a silver halide emulsion layer and a biaxially stretched poly(ethylene terephthalate) support, this application being a continuation of application Ser. No. 572,217, filed Aug. 15, 1966, now abandoned, which is a continuation-in-part of application Ser. No. 201,281, filed June 11, 1963, now abandoned.

In the manufacture of photographic film elements the adhesion of the hydrophilic gelatino silver halide emulsion layer to the hydrophobic support is impeded so that special subbing layers have to be applied to remedy this problem.

The subbing layers, which are particularly suited for fixing a silver halide emulsion layer to a cellulose ester or a polystyrene support do not satisfy if poly(ethylene terephthalate) is used as a support for the silver halide emulsion layer. Because in many cases and especially when a great dimensional stability of the photographic material is required, poly(ethylene terephthalate) is preferable to cellulose ester or to polystyrene as a support for a light-sensitive silver halide emulsion layer, the search is for a good subbing layer in this case.

Polyesters are very often used for the first subbing layer on a poly(ethylene terephthalate) support of a photographic film element.

From the United States patent specification 2,698,239 it is known to use in the preparation of a first subbing layer on a poly(ethylene terephthalate) support of a photographic film element, a highly polymeric tricomponent polyester of terephthalic acid, a polymethylene glycol having from 2 to 10 methylene groups and a compound taken from the group consisting of the polyethylene glycols containing 1 to 5 oxyethylene units, the saturated "ice aliphatic dicarboxylic acids of 4 to 16 carbon atoms and their acid chlorides, acid bromides and diesters with an alkanol of 1 to 6 carbon atoms, said polyester being soluble to the extent of at least /z% by weight in trichloroethylene.

In one of the specific examples of the same patent specification a polyester of ethylene glycol with terephthalic acid, isophthalic acid, and sebacic acid (50/25/25) 1s mentioned.

From the United States patent specification 2,874,046 it is known to apply to a poly(ethylene terephthalate) support of a photographic film element a first subbing layer, the film-forming agent of which essentially consists of a polyester of an 0a,}3-6thYl6l1iC3llY unsaturated aliphatic dicarboxylic acid and certain diols.

In the United States patent specification 3,178,287 for the manufacture of a photographic film element resins of the ethylene tere-isophthalate type are mentioned for the preparation of a first subbing layer on an oriented hydro-.- phobic polyethylene terephthalate support.

However, the adhesion properties of all these polyesters known from the art are insufiicient as will be shown further on in a specific example.

The most important object of the present invention is to provide a subbing for adhering the silver halide emulsion layer to a biaxially stretched poly(ethylene terephthalate) support, said subbing assuring an excellent adherence before, during as well as after processing of the photographic film element.

According to the present invention this object is accomplished by providing between the biaxially stretched poly- (ethylene terephthalate) support and the silver halide emulsion layer consecutively:

a first subbing layer comprising a polyester, which is soluble in chlorinated aliphatic hydrocarbons and which is prepared by condensation of at least one aliphatic diol with a diacid component consisting essentially of about 55 to mole percent of isophthalic acid, about 0 to 25 mole percent of terephthalic acid and about 0 to 20 mole percent of aliphatic saturated dicarboxylic acid, and

layer comprising a mixture of gelatin and cellulose nitrate.

According to another embodiment of the present invention the latter layer may be replaced by two separate layers. Indeed a cellulose nitrate layer and a gelatin layer can be applied consecutively to the first subbing layer.

The polyesters for the preparation of the said first subbing layer can be formed from the most divergent ratios of different diols. In order to avoid crystallization, the preferably used polyesters, however, contain in addition to ethylene glycol units at least 5 mole percent of neopentylene glycol units or 1,6-hexane diol units. The used polyesters preferably have a molecular weight of at least 4500 and a solubility of at least 10% in ethylene dichloride. Indeed, in order to obtain a good adhesion the layer comprising a polyester used according to the invention has to be applied from a solution containing preferably from about 3% to about 10% by weight of solid matter. Comparative solubiliti'es are listed in the following tableto show the influence of neopentylene glycol units or 1,6-hexane diol units introduced in the polyester structure on the solubility of the polyester used according to the invention.

PREPARATION 1 POLY NEOPENTYLENE GLYCOL *ISOPHTHALATE A mixture of 128 g. of dimethyl isophthalatc, 156 g. of neopentylene glycol, 21 mg. ofzinc acetate, 42 mg. of antimony trioxide, and mg.- of butyl orthotitanate is heated at 255 C. N f

Transesterification takes place and methanol is set free rapidly, which methanol is distilled over through a fractionating column. After 2 h. the transesterification is completed. Subsequently polycondensation is carried out un der reduced pressure'of 0.5 to 5 of Hg, the melt being stirred by a stream of pure nitrogen. The melt becomes very'yiscous and the polycondensation is continued for 3 h. [1 ]=O.26 d L/g. r

The polyester is composed of recurring units according to the following structural iorrnulap tate, and 20 mg. of antimony trioxide is melted at 255 C. After 1 h. of heating Whilst stirring with a moderate current of nitrogen, a completely clear melt is obtained.

Subsequently the waten rwhich is set free, is slowly distilled off? for 1 h. and the excess ethylene glycol is then distilled for /2 h. The polycondensation is then continued for 3 h. under a reduced pressure of 1 to 10 mm. of Hg. [1 ]=0.30 dL/g. N g

The resulting polyester is composed of recurring units according to the following structural formulae:

; El J I PREPARATION 3.--POLYESTER OF ISOlHTHALIC ACID, ETHYLENE GLYCOL, AND NEOPENTYL- ENE gLYcoL The polyester is composed of recurring units according to the following structural formulae:

H O l 8 -O-CH2-C(|3Hz-OC C- PREPARATION 4.-POLY(NEOPENTYLENE GLYCOL ISOPHTHALATE) A mixture of 29.1 g. of dimethyl isophthalate, 41.6 g. of neopentylene glycol, 3 mg. of zinc acetate, 6 mg. of antimony trioxide, and 6 mg. of methyl orthotitanate is heated at 282 C. under a nitrogen atmosphere.

The methanol, Which is set free, is distilled over for 2 h. through a fractionating column. Then the mixture is condensated for 4 h. at 282 C. under reduced pressure of 0.5 to 20 mm. of Hg. [1;]=0.20 dl./g.

The polyester is composed of recurring units according to the following structural formula:

PREPARATION 5.POLY(ETHYLENE GLYCOL ISOPHTHALATE A mixture of 50 g. of isophthalic acid, 50 g. of ethylene glycol, 10 mg. of zinc acetate, and g. of antimony trioxide is heated at 255 C. After 1 h. of reaction the solution becomes completely clear. The water formed during the reaction is distilled off for 1 h. at 255 C. through a fractionating column. Then the excess ethylene glycol is distilled off for /2 h. without column. While nitrogen is passed through the reaction mass, polycondensation takes place for 3 h. at 255 C. under reduced pressure of 2 to 10 mm. of Hg. [1 =0.26 dl./g.

The polyester is composed of recurring units according to the following structural formula:

PREPARATION 6.POLYESTER OF ISOPHTHALIC ACID, SEBACIC ACID, AND ETHYLENE GLYCOL A mixture of 39.8 g. of isophthalic acid, 13.8 g. of dimethyl sebacate, 41 g. of ethylene glycol, 10 mg. of zinc acetate, and 20 mg. of antimony trioxide is heated at 255 C. After 1 h. a completely clear solution is obtained. The water and the methanol, which are set free during the reaction, are distilled off for l h. through a fractionating column. Then the excess ethylene glycol is distilled off for /2 h. without column. The condensation reaction in the melt is continued for 2 h. under reduced pressure of 1 to 10 mm. of Hg at 255 C. [1;]:038 dl./g.

The polyester is composed of recurring units according to the following structural formulae:

6 PREPARATION 7.POLYESTER OF ISOPHTHALIC ACID, TEREPHTHALIC ACID, AND ETHYLENE GLYCOL A mixture of 40 g. of isophthalic acid, 11.75 g. of dimethyl terephthalate, 60 g. of ethylene glycol, 10 mg. of zinc acetate, and 20 mg. of antimony trioxide is heated at 255 C. After 1% h. of reaction the solution has become completely clear and the formed water and methanol are distilled off for 2 h. at 255 C. Polycondensation is then carried out for 3 h. at 255 C. and at reduced pressure while passing a nitrogen stream through the reaction mass. The mass becomes more viscous. [1 =0.28 dl./g.

The polyester is composed of recurring units corresponding to the following structural formulae:

PREPARATION 8.-POLYESTER OF ISOPHTHALIC ACID, TEREPHTHALIC ACID, ADIPIC ACID, AND ETHYLENE GLYCOL The polyester is prepared analogously to Preparation 7, starting, however, from 40 g. of isophthalic acid, 5.8 g. of dimethylterephthalate, 4.4 g. of adipic acid, and 60 g. of ethylene glycol. [1 ]=0.20 dl./ g.

The polyester is composed of recurring units according to the following structural formulae:

0 {o-(omu-o I il In the preparation of the first subbing layer the soluble polyesters are preferably applied to the biaxially stretched poly(ethylene terephthalate) support in the form of solutions in low-boiling organic solvents eg in chlorinated aliphatic hydrocarbons, such as ethylene dichloride, in dioxan, or in a mixture of chlorinated aliphatic hydrocarbons and dioxan, in which solvents the polyesters can be dissolved for at least 10% by weight.

A second thin subbing layer of cellulose nitrate and a third thin layer of gelatin are applied consecutively to the first subbing layer. These two layers can also be applied in the form of one single layer. The thickness of the whole subbing, consisting of the above 2 or 3 layers, generally varies between approximately 2 and 7 The transparency of the three superposed subbing layers is excellent. The flexibility of the photographic film element and the adhesion of the emulsion layer to the support in dry as well as in wet state is extremely satisfactory.

The following are examples of the use of subbing layers according to the present invention.

More particulars on the K-values of the cellulose nitrates mentioned in the examples can be found in H. Fikentscher, Cellulosechemie, vol. XIII, 1932, p. 58.

Example 1 A first subbing layer of the polyester according to Preparation 5 is coated from a 8% solution in ethylene dichloride on a biaxially stretched poly(ethylene tereph- 7 thalate) film of 100 t in thickness, so that 2 g. of polyester are present per sq. In.

On top thereof a second subbing layer is applied from the following solution, so that 1 1. thereof covers 30 sq. m. of film:

Cellulose nitrate (K-valuez13) g 6.25 Cellulose nitrate (K-valuez30) g 18.75 Methanol cm. 900 Methylene chloride cm. 100

Then a third subbing layer is applied from the following solution, so that 1 1. covers 50 sq. m. of film:

Gelatin g Water cm. 25% solution of salicylic acid in ethanol cm. 3O Methanol Crn. 919 10% aqueous solution of chrome alum cm. 3

Example 2 On a poly(ethylene terephthalate) support as described in Example 1 a first subbing layer is coated from a solution of the polyester of Preparation 3 in ethylene dichloride, in a ratio of 1.5 g. of polyester per sq. m. The second and third subbing layers are applied as in Example 1.

On the dry subbing thus obtained a common gelatino silver halide emulsion layer is coated.

Scratching tests, which are carried out after drying of the resulting photographic film element as well as after wetting it in the photographic baths, show that a good adhesion is obtained between the biaxially stretched poly (ethylene terephthalate) support and the gelatino silver halide emulsion layer.

Example 3 A poly(ethylene terephthalate) support as described in Example 1 is coated with a first subbing layer from a solution of the polyester of Preparation 2 in ethylene dichloride in a ratio of 1 g. of polyester per sq. m. The second and the third subbing layers are applied as in Example 1.

Then a common gelatino silver halide emulsion layer is coated on the dry subbing.

Scratching tests, which are carried out after drying of the resulting photographic film element as well as after wetting it in the photographic baths, show that a good adhesion is obtained between the biaxially stretched poly (ethylene terephthalate) support and the gelatino silver halide emulsion layer.

Example 4 A biaxially stretched poly(ethylene terephthalate) support of 75 in thickness is coated with a first subbing layer from a 8% solution of the polyester of Preparation 7 in ethylene dichloride in such a way, that 1.5 g. of polyester is present per sq. m. of support.

On top thereof a second subbing layer is applied from the following solution, so that 1 1. thereof covers 30 sq. m. of paper:

Cellulose nitrate (K-valuez30) g 25 Methanol cm. 900 Methylene chloride cm. 100

The third subbing layer is coated as in Example 1. After having been dried, the subbing is coated with a common gelatino silver halide emulsion layer.

Scratching tests, which are carried out after drying of the resulting photographic film element as well as after wetting it in the photographic baths, show that a good adhesion is obtained between the biaxially stretched poly (ethylene terephthalate) support and the gelatino silver halide emulsion layer.

Example 5 A poly(ethylene terephthalate) support as described in Example 4 is coated with the same first subbing layer as in Example 1. On top thereof a second subbing layer is applied from the following solution, so that 1 1. thereof covers 25 sq. m. of support:

Cellulose nitrate (K-value: 15) g 12.5 Cellulose nitrate (K-value: 30) g 12.5 Methanol cm. 900 Methylene chloride cm.

The third subbing layer is applied as in Example 1.

A common gelatino silver halide emulsion layer is then applied to the dry subbing layer.

Scratching tests, which are carried out after drying of the resulting photographic film element as well as after wetting it in the photographic baths, show that a good adhesion is obtained between the biaxially stretched poly- (ethylene terephthalate) support and the gelatino silver halide emulsion layer.

Example 6 A poly (ethylene terephthalate) support as described in Example 1 is coated with a first subbing layer from a 4% solution of the polyester of Preparation 6 in ethylene dichloride, in a ratio of 1.5 g. of polyester per sq. m. of support. After drying, a second and a third layer are applied thereto as in Example 1.

Then the dry subbing is coated with a common gelatino silver halide emulsion layer.

Scratching tests, which are carried out after drying of the resulting photographic material as well as after wetting it in the photographic baths, show that a good adhesion is obtained between the poly(ethylene terephthalate) support and the gelatino silver halide emulsion layer.

Example 7 A poly (ethylene terephthalate) support as described in Example 1 is coated with a first subbing layer from a 8% solution of the polyester of Preparation 8 in ethylene dichloride in a ratio of 1.3 g. of polyester per sq. m. of support. After drying, a second subbing layer is applied from the following composition in a ratio of l 1. thereof per 40 sq. m.:

Subsequently the dry subbing is coated with a common gelatino silver halide emulsion layer.

Scratching tests, which are carried out after drying of the resulting photographic material as well as after wetting it in the photographic baths, show that a good adhesion is obtained between the poly(ethylene terephthalate) support and the gelatino silver halide emulsion layer.

Example 8 On a biaxially stretched poly(ethylene terphthalate) support having a thickness of 100 1., a subbing layer of the polyester of ethylene glycol and isophthalic acid prepared as described in Preparation 5 is coated from a 7% solution in ethylene dichloride. After drying, a gelatincellulose nitrate subbing layer is applied thereto as described in Example 7. Subsequently a common gelatino silver halide emulsion layer is applied to the dried material.

A second photographic film element is prepared in an analogous manner, with the proviso, however, that the polyester of ethylene glycol and isophthalic acid is replaced by the polyester prepared according to Preparation 8.

A third photographic film element is prepared by coating a biaxially stretched poly(ethylene terephthalate) support having a thickness of 100 with a subbing according to the United States patent specification 2,698,239 and then with a common gelatino silver halide emulsion layer.

The subbing comprises consecutively:

A layer of a polyester of ethylene glycol, terephthalic acid, isophthalic acid and sebacic acid (50/25/25) (see the example 9 of said United States patent specification) coated from a 3% solution in trichloroethylene, and

A thin layer coated from a composition comprising:

Gelatin g 1 Acetic acid ccs 4 Methanol ccs 30 Trichloroethylene ccs 65 A fourth photographic film element is prepared by coating a biaxially stretched poly(ethylene terephthalate) support having a thickness of 100 with a first subbing layer comprising a polyester, which is closely related with the polyesters of the first subbing layer of the photographic film element according to the present invention and which is within the broad scope of polyesters of the ethylene tereisophthalate type disclosed in the United States patent specification 3,178,287.

This polyester subbing layer is applied from the following coating solution disclosed in said United States patent specification:

Acetone 55 Dioxan 45 Cellulose nitrate 2.5

Polyester of ethyleneglycol with terephthalic acid and isophthalic acid (50/50) 5 Polyester of ethylene glycol with terephthalic acid and isophthalic acid (60/40) 2.5

After drying, a second subbing layer is applied from the following coating composition (see the said United States patent specification):

Gelatin 2 Acetic acid 6 Water 3 Methanol 63 Acetone 22 Methylenediol 3 Cellulose nitrate 1 Finally, a common gelatino silver halide emulsion layer is applied on top of the subbing layers.

A fifth photographic film element is prepared by coating a biaxially stretched poly(ethylene terephthalate) support having a thickness of 100g with a first thin subbing layer of the polyester of ethylene glycol, terephthalic acid, and maleic anhydride, as described in Example 1 of said United States patent specification, 2,874,046, from a 5% solution in ethylene dichloride.

Subsequently a second thin subbing layer is applied from the following coating solution:

Cellulose nitrate g 1.5

Ethyl acetate ccs Butyl acetate ccs 25 Ethanol ccs 60 A gelatin subbing layer is then applied from a solution comprising:

Ccs. Gelatin 10 Water 63 10% solution of phthalic acid in methanol l6 1% solution of formaldehyde in methanol 800 Finally, a common gelatino silver halide emulsion layer is applied on top of the subbing layers described.

The adhesion of the emulsion layer to the support is tested for all 5 film elements before processing, after fixing, after rinsing and after drying again. The adhesion tests of dry material are carried out by applying an adhesive tape to the emulsion layer and tearing ofif this tape with a jerk or by tearing the photographic film element.

The adhesion tests of wet material are carried out by scratching the emulsion layer by means of a pointed member and then rubbing it with a finger.

These tests proved that the adhesion of the emulsion layer to the support is excellent for the first two elements, before processing as well as after fixing, after rinsing, and after drying.

The adhesion of the emulsion layer in the third and the fifth film element is bad in dry as well as in Wet condition.

The adhesion of the. fourth film element is good in wet condition, but bad in dry condition, especially after processing of the film element.

We claim:

1. A photographic film element comprising consecutively:

a biaxially stretched poly(ethylene terephthalate) support a layer consisting essentially of a polyester, which is soluble in chlorinated aliphatic hydrocarbons and which is prepared by condensation of at least one aliphatic diol with a diacid component essentially consisting of about 55 to mole percent of isophthalic acid, about 0 to 25 mole percent of terephthalic acid,

and about 0 to 20 mole percent of aliphatic saturated dicarboxylic acid,

a layer comprising a mixture of gelatin and cellulose nitrate, and

a light-sensitive silver halide emulsion layer.

2. A photographic film element comprising consecutively:

a biaxially stretched poly(ethylene terephthalate) support,

a layer consisting essentially of a polyester, which is soluble in chlorinated aliphatic hydrocarbons and which is prepared by condensation of at least one aliphatic diol with a diacid component consisting essentially of about 55 to 100 mole percent of isophthalic acid, about 0 to 25 mole percent of terephthalic acid, and about 0 to 20 mole percent of aliphatic saturated dicarboxylic acid,

a cellulose nitrate layer,

a gelatin layer, and

a light-sensitive silver halide emulsion layer.

3. The film element of claim 1 wherein said polyester, which is soluble in chlorinated aliphatic hydrocarbons, has a molecular weight of at least about 4500 and a solubility in ethylene dichloride of at least about 10% by weight.

4. The film element of claim 2 wherein said polyester, which is soluble in chlorinated aliphatic hydrocarbons, has a molecular weight of at least about 4500 and a solubility in ethylene dichloride of at least about 10% by weight.

5. The film element of claim 1 wherein said aliphatic diol of the polyester, which is soluble in chlorinated aliphatic hydrocarbons, comprises at least about 5 mole percent of a 'member selected from the group consisting of neopentylene glycol and 1,6-hexane diol.

6. The film element of claim 5 wherein the remainder of said aliphatic diol is ethylene glycol.

7. The film element of claim 2 wherein said aliphatic diol of the polyester, which is soluble in chlorinated aliphatic hydrocarbons, comprises at least about 5 mole percent of a member selected from the group consisting of neopentylene glycol and 1,6-hexane diol.

8. The film element of claim 7, wherein the remainder of aliphatic diol is ethylene glycol.

9. The film element of claim 1, wherein the light-sensitive silver halide emulsion layer is a gelatino silver halide emulsion layer.

10. The film element of claim 2 wherein the light-sensitive silver halide emulsion layer is a gelatino silver halide emulsion layer.

11. The film element of claim 1 wherein said polyester is polyethylene isophthalate.

12. The film element of claim 2 wherein said polyester is polyethylene isophthalate.

References Cited UNITED STATES PATENTS NORMAN G. TORCHIN, Primary Examiner R. H. SMITH, Assistant Examiner US. Cl. X.R. 

